Geological investigations in the centre of Haarlem (the Netherlands) and the development of the river Spaarne

Abstract

The Spaarne river, exists since the Early Subboreal and drains into the former IJ estuary. Its main sand deposits date from the Early Subatlantic, other deposits from after the beginning of the Christian era. Sands of medium grain size are obviously derived from reworked dune and beach sands. They were deposited partially as point-bar deposits, but dune sands blown into the water of the Spaarne may also be present. Substantial amounts of organic material were deposited after the beginning of the Christian era. A clay bed Bakenes clay, covers the much older Holland Peat along both sides of the Spaarne. The clay probably dates from the XIIth century and reflects a period of flooding, including some storm surges which are mentioned in historical sources. In late medieval times a strip of land along the Spaarne was reclaimed; the resulting shift of the Spaarne bank is discussed.